Conventional linear shaped LED luminaires used for lighting applications typically make use of a tightly spaced array of low to medium power LED emitters. The use of a tightly spaced LED array makes the luminaire capable of casting a uniform light pattern at short distances.
Due to the somewhat inefficient power conversion characteristics of LED emitters however, a tightly spaced LED array with a large number of LED emitters also results in increased power dissipation for the luminaire in relation to light output. Thus, as the number of LED emitters is increased, more of the available energy is dissipated in the form of heat as opposed to generating usable light output. In addition, the low to medium power LED emitters employed in tightly spaced LED arrays tend to have poor thermal transfer characteristics. These two factors combine to either limit the maximum power dissipation for the luminaire or to increase the size and weight of the heat sink surface required to prevent irreparable LED junction damage.
Conventional LED luminaires used for lighting applications typically make use of a diffused lens or some other form of secondary optics in order to blend the produced light pattern into a uniform presentation at close distances. Any such diffusion or optics however, results in a substantial reduction in light output due to transmission losses in the diffuser or optics material. As a result, the LED array must be driven at a higher level in order to offset these light losses, resulting in higher luminaire power consumption.
Another disadvantage of conventional LED luminaire designs relates to when they are employed in wall and/or ceiling applications where the luminaire is visible to the observer, such as, for example, within an aircraft. In such an application, the LED presentation must be heavily diffused otherwise the observer will be able to view the LED point sources in the luminaire directly. Direct viewing of the LED point sources is not only unsightly, but in addition, it is very unpleasant for the observer.